diff --git a/.claude-plugin/marketplace.json b/.claude-plugin/marketplace.json
index 5af5e33..59e27a3 100644
--- a/.claude-plugin/marketplace.json
+++ b/.claude-plugin/marketplace.json
@@ -35,6 +35,19 @@
       "license": "Apache-2.0",
       "keywords": ["android", "clone", "feasibility", "effort-estimation", "market-analysis"],
       "category": "security"
+    },
+    {
+      "name": "market-research",
+      "source": "./plugins/market-research",
+      "description": "Research the app/game market and surface scored, non-repeating clone candidates that feed into clone-app.",
+      "version": "0.1.0",
+      "author": {
+        "name": "masa2146"
+      },
+      "repository": "https://github.com/masa2146/clone-app-skill",
+      "license": "Apache-2.0",
+      "keywords": ["market-research", "app-discovery", "trends", "clone"],
+      "category": "security"
     }
   ]
 }
diff --git a/plugins/market-research/.claude-plugin/plugin.json b/plugins/market-research/.claude-plugin/plugin.json
new file mode 100644
index 0000000..655644f
--- /dev/null
+++ b/plugins/market-research/.claude-plugin/plugin.json
@@ -0,0 +1,13 @@
+{
+  "name": "market-research",
+  "version": "0.1.0",
+  "description": "Autonomously research the app/game market (free web + LLM trend synthesis) and surface scored, non-repeating clone candidates that feed into the clone-app skill.",
+  "author": {
+    "name": "masa2146"
+  },
+  "repository": "https://github.com/masa2146/clone-app-skill",
+  "license": "Apache-2.0",
+  "keywords": ["market-research", "app-discovery", "trends", "clone", "play-store", "app-store"],
+  "skills": "./skills/",
+  "commands": "./commands/"
+}
diff --git a/plugins/market-research/README.md b/plugins/market-research/README.md
new file mode 100644
index 0000000..8c8ccbb
--- /dev/null
+++ b/plugins/market-research/README.md
@@ -0,0 +1,37 @@
+# market-research
+
+A Claude Code plugin that autonomously researches the app/game market and surfaces
+scored, non-repeating clone candidates, then hands user-chosen candidates to the
+`clone-app` plugin for feasibility analysis.
+
+## What it does
+
+`/market-research` runs a 6-phase workflow:
+
+0. **Seed rotation** — pick varied search angles (category × region × niche) so runs differ.
+1. **Gather** — App Store RSS chart data (`fetch-charts.py`) + free web search for trends.
+2. **Synthesize** — cluster findings into ≥10 distinct app/game ideas.
+3. **Score** — composite score: cloneability + market opportunity + monetization fit.
+4. **Dedup** — exclude anything already in `./work/market-research/history.json`.
+5. **Present + handoff** — show the ranked table; chosen candidates flow into `clone-app`.
+
+## State
+
+Written under `./work/market-research/` in your current directory:
+- `history.json` — every past suggestion; the non-repeat memory.
+- `research-<date>.md` — the full report for a run.
+
+## Scripts
+
+- `scripts/fetch-charts.py` — fetch App Store RSS chart feeds → normalized JSON.
+- `scripts/history.py` — read / append / dedup the suggestion history.
+
+Python is stdlib-only. Tests run offline against `tests/fixtures/`:
+
+```bash
+bash plugins/market-research/tests/run-all.sh
+```
+
+## Effort convention
+
+Effort is measured in **AI Sprints** (one focused Claude session), never calendar time.
diff --git a/plugins/market-research/commands/market-research.md b/plugins/market-research/commands/market-research.md
new file mode 100644
index 0000000..45f9202
--- /dev/null
+++ b/plugins/market-research/commands/market-research.md
@@ -0,0 +1,30 @@
+---
+allowed-tools: Bash, Read, Glob, Grep, Write, Edit, WebFetch, WebSearch, Skill
+description: Research the app/game market and surface scored, non-repeating clone candidates
+user-invocable: true
+argument-hint: [optional focus, e.g. "casual games" or "fintech LATAM"]
+argument: optional market focus or angle (optional)
+---
+
+# /market-research
+
+Run the market-research workflow: scan the market, score candidates, hand picks to clone-app.
+
+## Instructions
+
+Follow the market-research skill workflow in
+`${CLAUDE_PLUGIN_ROOT}/skills/market-research/SKILL.md` exactly, phases 0 through 5.
+
+### Step 1: Optional focus
+If the user passed a focus argument (e.g. "casual games", "fintech LATAM"), bias
+the Phase 0 seed selection toward it. Otherwise rotate seeds normally.
+
+### Step 2: Run the skill
+Execute Phase 0 → Phase 5 from SKILL.md. Pause for the user at Phase 5 (pick
+candidates to hand to clone-app).
+
+### Step 3: Deliver
+Ensure the report is written to `./work/market-research/research-<date>.md` and
+the new suggestions are appended to `./work/market-research/history.json`. For
+each candidate the user picks, resolve it to a Google Play package/URL and invoke
+the `clone-app` skill on it.
diff --git a/plugins/market-research/tests/smoke-structure.sh b/plugins/market-research/tests/smoke-structure.sh
new file mode 100755
index 0000000..6fa78ac
--- /dev/null
+++ b/plugins/market-research/tests/smoke-structure.sh
@@ -0,0 +1,32 @@
+#!/usr/bin/env bash
+set -uo pipefail
+ROOT="$(cd "$(dirname "$0")/../../.." && pwd)"   # repo root
+P="$ROOT/plugins/market-research"
+fail=0
+must_exist() { [[ -e "$1" ]] && echo "PASS exists: ${1#$ROOT/}" || { echo "FAIL missing: ${1#$ROOT/}"; fail=1; }; }
+must_exec()  { [[ -x "$1" ]] && echo "PASS exec: ${1#$ROOT/}"   || { echo "FAIL not exec: ${1#$ROOT/}"; fail=1; }; }
+
+must_exist "$P/.claude-plugin/plugin.json"
+must_exist "$P/commands/market-research.md"
+must_exist "$P/README.md"
+must_exist "$P/skills/market-research/SKILL.md"
+for s in fetch-charts.py history.py; do
+  must_exist "$P/skills/market-research/scripts/$s"
+  must_exec  "$P/skills/market-research/scripts/$s"
+done
+for r in research-angles scoring-guide report-template; do
+  must_exist "$P/skills/market-research/references/$r.md"
+done
+
+# JSON validity: plugin manifest + marketplace
+python3 -c "import json;json.load(open('$P/.claude-plugin/plugin.json'));json.load(open('$ROOT/.claude-plugin/marketplace.json'))" \
+  && echo "PASS json valid" || { echo "FAIL json invalid"; fail=1; }
+
+# all three plugins present in marketplace
+python3 -c "
+import json;d=json.load(open('$ROOT/.claude-plugin/marketplace.json'))
+names=[p['name'] for p in d['plugins']]
+assert 'market-research' in names and 'clone-app' in names and 'android-reverse-engineering' in names
+print('PASS marketplace has all three plugins')" || { echo "FAIL marketplace entries"; fail=1; }
+
+exit $fail